In numerous fields, there is a need for linear signal amplification exhibiting a high degree of power efficiency. An approach in keeping with this is to linearize the non-linear characteristic of a power amplifier (PA: Power Amplifier) by pre-distorting the signal in the digital baseband. However, the non-linearity keeps changing, for example, due to ageing and temperature-dependent components. With some methods, such as digital adaptive pre-distortion, the envelope of the transmitted signal has to be recovered with the aid of a feedback path, consisting, in particular, of a coupler, demodulator, and ADC (ADC: Analog-to-Digital Converter), as it is required for adaptation.
Classical pre-distortion employing coherent demodulation is hardware-intensive (since a complete receiving path is required), expensive and, in terms of energy consumption, inefficient especially in the mid-power range. Stringent demands are additionally placed on linearity in the feedback path and on determining the delay in the measured signal.
Because of the cited problems, no PA linearizing methods based on digital pre-distortion have, to date, been implemented in commercial mobile telephone systems (at least none are known).
The present invention seeks to provide a linear signal amplification that can be employed particularly in mobile radio arrangements such as mobile radio devices or mobile telephones.